fsdev/virtfs-proxy-helper.c

   1 /*
   2  * Helper for QEMU Proxy FS Driver
   3  * Copyright IBM, Corp. 2011
   4  *
   5  * Authors:
   6  * M. Mohan Kumar <mohan@in.ibm.com>
   7  *
   8  * This work is licensed under the terms of the GNU GPL, version 2. See
   9  * the COPYING file in the top-level directory.
  10  */
  11
  12 #include "qemu/osdep.h"
  13 #include <sys/resource.h>
  14 #include <getopt.h>
  15 #include <syslog.h>
  16 #include <sys/capability.h>
  17 #include <sys/fsuid.h>
  18 #include <sys/vfs.h>
  19 #include <sys/ioctl.h>
  20 #include <linux/fs.h>
  21 #ifdef CONFIG_LINUX_MAGIC_H
  22 #include <linux/magic.h>
  23 #endif
  24 #include "qemu-common.h"
  25 #include "qemu/sockets.h"
  26 #include "qemu/xattr.h"
  27 #include "9p-iov-marshal.h"
  28 #include "hw/9pfs/9p-proxy.h"
  29 #include "fsdev/9p-iov-marshal.h"
  30
  31 #define PROGNAME "virtfs-proxy-helper"
  32
  33 #ifndef XFS_SUPER_MAGIC
  34 #define XFS_SUPER_MAGIC  0x58465342
  35 #endif
  36 #ifndef EXT2_SUPER_MAGIC
  37 #define EXT2_SUPER_MAGIC 0xEF53
  38 #endif
  39 #ifndef REISERFS_SUPER_MAGIC
  40 #define REISERFS_SUPER_MAGIC 0x52654973
  41 #endif
  42 #ifndef BTRFS_SUPER_MAGIC
  43 #define BTRFS_SUPER_MAGIC 0x9123683E
  44 #endif
  45
  46 static struct option helper_opts[] = {
  47     {"fd", required_argument, NULL, 'f'},
  48     {"path", required_argument, NULL, 'p'},
  49     {"nodaemon", no_argument, NULL, 'n'},
  50     {"socket", required_argument, NULL, 's'},
  51     {"uid", required_argument, NULL, 'u'},
  52     {"gid", required_argument, NULL, 'g'},
  53     {},
  54 };
  55
  56 static bool is_daemon;
  57 static bool get_version; /* IOC getversion IOCTL supported */
  58
  59 static void GCC_FMT_ATTR(2, 3) do_log(int loglevel, const char *format, ...)
  60 {
  61     va_list ap;
  62
  63     va_start(ap, format);
  64     if (is_daemon) {
  65         vsyslog(LOG_CRIT, format, ap);
  66     } else {
  67         vfprintf(stderr, format, ap);
  68     }
  69     va_end(ap);
  70 }
  71
  72 static void do_perror(const char *string)
  73 {
  74     if (is_daemon) {
  75         syslog(LOG_CRIT, "%s:%s", string, strerror(errno));
  76     } else {
  77         fprintf(stderr, "%s:%s\n", string, strerror(errno));
  78     }
  79 }
  80
  81 static int do_cap_set(cap_value_t *cap_value, int size, int reset)
  82 {
  83     cap_t caps;
  84     if (reset) {
  85         /*
  86          * Start with an empty set and set permitted and effective
  87          */
  88         caps = cap_init();
  89         if (caps == NULL) {
  90             do_perror("cap_init");
  91             return -1;
  92         }
  93         if (cap_set_flag(caps, CAP_PERMITTED, size, cap_value, CAP_SET) < 0) {
  94             do_perror("cap_set_flag");
  95             goto error;
  96         }
  97     } else {
  98         caps = cap_get_proc();
  99         if (!caps) {
 100             do_perror("cap_get_proc");
 101             return -1;
 102         }
 103     }
 104     if (cap_set_flag(caps, CAP_EFFECTIVE, size, cap_value, CAP_SET) < 0) {
 105         do_perror("cap_set_flag");
 106         goto error;
 107     }
 108     if (cap_set_proc(caps) < 0) {
 109         do_perror("cap_set_proc");
 110         goto error;
 111     }
 112     cap_free(caps);
 113     return 0;
 114
 115 error:
 116     cap_free(caps);
 117     return -1;
 118 }
 119
 120 static int init_capabilities(void)
 121 {
 122     /* helper needs following capabilities only */
 123     cap_value_t cap_list[] = {
 124         CAP_CHOWN,
 125         CAP_DAC_OVERRIDE,
 126         CAP_FOWNER,
 127         CAP_FSETID,
 128         CAP_SETGID,
 129         CAP_MKNOD,
 130         CAP_SETUID,
 131     };
 132     return do_cap_set(cap_list, ARRAY_SIZE(cap_list), 1);
 133 }
 134
 135 static int socket_read(int sockfd, void *buff, ssize_t size)
 136 {
 137     ssize_t retval, total = 0;
 138
 139     while (size) {
 140         retval = read(sockfd, buff, size);
 141         if (retval == 0) {
 142             return -EIO;
 143         }
 144         if (retval < 0) {
 145             if (errno == EINTR) {
 146                 continue;
 147             }
 148             return -errno;
 149         }
 150         size -= retval;
 151         buff += retval;
 152         total += retval;
 153     }
 154     return total;
 155 }
 156
 157 static int socket_write(int sockfd, void *buff, ssize_t size)
 158 {
 159     ssize_t retval, total = 0;
 160
 161     while (size) {
 162         retval = write(sockfd, buff, size);
 163         if (retval < 0) {
 164             if (errno == EINTR) {
 165                 continue;
 166             }
 167             return -errno;
 168         }
 169         size -= retval;
 170         buff += retval;
 171         total += retval;
 172     }
 173     return total;
 174 }
 175
 176 static int read_request(int sockfd, struct iovec *iovec, ProxyHeader *header)
 177 {
 178     int retval;
 179
 180     /*
 181      * read the request header.
 182      */
 183     iovec->iov_len = 0;
 184     retval = socket_read(sockfd, iovec->iov_base, PROXY_HDR_SZ);
 185     if (retval < 0) {
 186         return retval;
 187     }
 188     iovec->iov_len = PROXY_HDR_SZ;
 189     retval = proxy_unmarshal(iovec, 0, "dd", &header->type, &header->size);
 190     if (retval < 0) {
 191         return retval;
 192     }
 193     /*
 194      * We can't process message.size > PROXY_MAX_IO_SZ.
 195      * Treat it as fatal error
 196      */
 197     if (header->size > PROXY_MAX_IO_SZ) {
 198         return -ENOBUFS;
 199     }
 200     retval = socket_read(sockfd, iovec->iov_base + PROXY_HDR_SZ, header->size);
 201     if (retval < 0) {
 202         return retval;
 203     }
 204     iovec->iov_len += header->size;
 205     return 0;
 206 }
 207
 208 static int send_fd(int sockfd, int fd)
 209 {
 210     struct msghdr msg;
 211     struct iovec iov;
 212     int retval, data;
 213     struct cmsghdr *cmsg;
 214     union MsgControl msg_control;
 215
 216     iov.iov_base = &data;
 217     iov.iov_len = sizeof(data);
 218
 219     memset(&msg, 0, sizeof(msg));
 220     msg.msg_iov = &iov;
 221     msg.msg_iovlen = 1;
 222     /* No ancillary data on error */
 223     if (fd < 0) {
 224         /* fd is really negative errno if the request failed  */
 225         data = fd;
 226     } else {
 227         data = V9FS_FD_VALID;
 228         msg.msg_control = &msg_control;
 229         msg.msg_controllen = sizeof(msg_control);
 230
 231         cmsg = &msg_control.cmsg;
 232         cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
 233         cmsg->cmsg_level = SOL_SOCKET;
 234         cmsg->cmsg_type = SCM_RIGHTS;
 235         memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));
 236     }
 237
 238     do {
 239         retval = sendmsg(sockfd, &msg, 0);
 240     } while (retval < 0 && errno == EINTR);
 241     if (fd >= 0) {
 242         close(fd);
 243     }
 244     if (retval < 0) {
 245         return retval;
 246     }
 247     return 0;
 248 }
 249
 250 static int send_status(int sockfd, struct iovec *iovec, int status)
 251 {
 252     ProxyHeader header;
 253     int retval, msg_size;
 254
 255     if (status < 0) {
 256         header.type = T_ERROR;
 257     } else {
 258         header.type = T_SUCCESS;
 259     }
 260     header.size = sizeof(status);
 261     /*
 262      * marshal the return status. We don't check error.
 263      * because we are sure we have enough space for the status
 264      */
 265     msg_size = proxy_marshal(iovec, 0, "ddd", header.type,
 266                              header.size, status);
 267     if (msg_size < 0) {
 268         return msg_size;
 269     }
 270     retval = socket_write(sockfd, iovec->iov_base, msg_size);
 271     if (retval < 0) {
 272         return retval;
 273     }
 274     return 0;
 275 }
 276
 277 /*
 278  * from man 7 capabilities, section
 279  * Effect of User ID Changes on Capabilities:
 280  * If the effective user ID is changed from nonzero to 0, then the permitted
 281  * set is copied to the effective set.  If the effective user ID is changed
 282  * from 0 to nonzero, then all capabilities are are cleared from the effective
 283  * set.
 284  *
 285  * The setfsuid/setfsgid man pages warn that changing the effective user ID may
 286  * expose the program to unwanted signals, but this is not true anymore: for an
 287  * unprivileged (without CAP_KILL) program to send a signal, the real or
 288  * effective user ID of the sending process must equal the real or saved user
 289  * ID of the target process.  Even when dropping privileges, it is enough to
 290  * keep the saved UID to a "privileged" value and virtfs-proxy-helper won't
 291  * be exposed to signals.  So just use setresuid/setresgid.
 292  */
 293 static int setugid(int uid, int gid, int *suid, int *sgid)
 294 {
 295     int retval;
 296
 297     /*
 298      * We still need DAC_OVERRIDE because we don't change
 299      * supplementary group ids, and hence may be subjected DAC rules
 300      */
 301     cap_value_t cap_list[] = {
 302         CAP_DAC_OVERRIDE,
 303     };
 304
 305     *suid = geteuid();
 306     *sgid = getegid();
 307
 308     if (setresgid(-1, gid, *sgid) == -1) {
 309         retval = -errno;
 310         goto err_out;
 311     }
 312
 313     if (setresuid(-1, uid, *suid) == -1) {
 314         retval = -errno;
 315         goto err_sgid;
 316     }
 317
 318     if (uid != 0 || gid != 0) {
 319         if (do_cap_set(cap_list, ARRAY_SIZE(cap_list), 0) < 0) {
 320             retval = -errno;
 321             goto err_suid;
 322         }
 323     }
 324     return 0;
 325
 326 err_suid:
 327     if (setresuid(-1, *suid, *suid) == -1) {
 328         abort();
 329     }
 330 err_sgid:
 331     if (setresgid(-1, *sgid, *sgid) == -1) {
 332         abort();
 333     }
 334 err_out:
 335     return retval;
 336 }
 337
 338 /*
 339  * This is used to reset the ugid back with the saved values
 340  * There is nothing much we can do checking error values here.
 341  */
 342 static void resetugid(int suid, int sgid)
 343 {
 344     if (setresgid(-1, sgid, sgid) == -1) {
 345         abort();
 346     }
 347     if (setresuid(-1, suid, suid) == -1) {
 348         abort();
 349     }
 350 }
 351
 352 /*
 353  * send response in two parts
 354  * 1) ProxyHeader
 355  * 2) Response or error status
 356  * This function should be called with marshaled response
 357  * send_response constructs header part and error part only.
 358  * send response sends {ProxyHeader,Response} if the request was success
 359  * otherwise sends {ProxyHeader,error status}
 360  */
 361 static int send_response(int sock, struct iovec *iovec, int size)
 362 {
 363     int retval;
 364     ProxyHeader header;
 365
 366     /*
 367      * If response size exceeds available iovec->iov_len,
 368      * we return ENOBUFS
 369      */
 370     if (size > PROXY_MAX_IO_SZ) {
 371         size = -ENOBUFS;
 372     }
 373
 374     if (size < 0) {
 375         /*
 376          * In case of error we would not have got the error encoded
 377          * already so encode the error here.
 378          */
 379         header.type = T_ERROR;
 380         header.size = sizeof(size);
 381         proxy_marshal(iovec, PROXY_HDR_SZ, "d", size);
 382     } else {
 383         header.type = T_SUCCESS;
 384         header.size = size;
 385     }
 386     proxy_marshal(iovec, 0, "dd", header.type, header.size);
 387     retval = socket_write(sock, iovec->iov_base, header.size + PROXY_HDR_SZ);
 388     if (retval < 0) {
 389         return retval;
 390     }
 391     return 0;
 392 }
 393
 394 /*
 395  * gets generation number
 396  * returns -errno on failure and sizeof(generation number) on success
 397  */
 398 static int do_getversion(struct iovec *iovec, struct iovec *out_iovec)
 399 {
 400     uint64_t version;
 401     int retval = -ENOTTY;
 402 #ifdef FS_IOC_GETVERSION
 403     int fd;
 404     V9fsString path;
 405 #endif
 406
 407
 408     /* no need to issue ioctl */
 409     if (!get_version) {
 410         version = 0;
 411         retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "q", version);
 412         return retval;
 413     }
 414 #ifdef FS_IOC_GETVERSION
 415     retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "s", &path);
 416     if (retval < 0) {
 417         return retval;
 418     }
 419
 420     fd = open(path.data, O_RDONLY);
 421     if (fd < 0) {
 422         retval = -errno;
 423         goto err_out;
 424     }
 425     if (ioctl(fd, FS_IOC_GETVERSION, &version) < 0) {
 426         retval = -errno;
 427     } else {
 428         retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "q", version);
 429     }
 430     close(fd);
 431 err_out:
 432     v9fs_string_free(&path);
 433 #endif
 434     return retval;
 435 }
 436
 437 static int do_getxattr(int type, struct iovec *iovec, struct iovec *out_iovec)
 438 {
 439     int size = 0, offset, retval;
 440     V9fsString path, name, xattr;
 441
 442     v9fs_string_init(&xattr);
 443     v9fs_string_init(&path);
 444     retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "ds", &size, &path);
 445     if (retval < 0) {
 446         return retval;
 447     }
 448     offset = PROXY_HDR_SZ + retval;
 449
 450     if (size) {
 451         xattr.data = g_malloc(size);
 452         xattr.size = size;
 453     }
 454     switch (type) {
 455     case T_LGETXATTR:
 456         v9fs_string_init(&name);
 457         retval = proxy_unmarshal(iovec, offset, "s", &name);
 458         if (retval > 0) {
 459             retval = lgetxattr(path.data, name.data, xattr.data, size);
 460             if (retval < 0) {
 461                 retval = -errno;
 462             } else {
 463                 xattr.size = retval;
 464             }
 465         }
 466         v9fs_string_free(&name);
 467         break;
 468     case T_LLISTXATTR:
 469         retval = llistxattr(path.data, xattr.data, size);
 470         if (retval < 0) {
 471             retval = -errno;
 472         } else {
 473             xattr.size = retval;
 474         }
 475         break;
 476     }
 477     if (retval < 0) {
 478         goto err_out;
 479     }
 480
 481     if (!size) {
 482         proxy_marshal(out_iovec, PROXY_HDR_SZ, "d", retval);
 483         retval = sizeof(retval);
 484     } else {
 485         retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "s", &xattr);
 486     }
 487 err_out:
 488     v9fs_string_free(&xattr);
 489     v9fs_string_free(&path);
 490     return retval;
 491 }
 492
 493 static void stat_to_prstat(ProxyStat *pr_stat, struct stat *stat)
 494 {
 495     memset(pr_stat, 0, sizeof(*pr_stat));
 496     pr_stat->st_dev = stat->st_dev;
 497     pr_stat->st_ino = stat->st_ino;
 498     pr_stat->st_nlink = stat->st_nlink;
 499     pr_stat->st_mode = stat->st_mode;
 500     pr_stat->st_uid = stat->st_uid;
 501     pr_stat->st_gid = stat->st_gid;
 502     pr_stat->st_rdev = stat->st_rdev;
 503     pr_stat->st_size = stat->st_size;
 504     pr_stat->st_blksize = stat->st_blksize;
 505     pr_stat->st_blocks = stat->st_blocks;
 506     pr_stat->st_atim_sec = stat->st_atim.tv_sec;
 507     pr_stat->st_atim_nsec = stat->st_atim.tv_nsec;
 508     pr_stat->st_mtim_sec = stat->st_mtim.tv_sec;
 509     pr_stat->st_mtim_nsec = stat->st_mtim.tv_nsec;
 510     pr_stat->st_ctim_sec = stat->st_ctim.tv_sec;
 511     pr_stat->st_ctim_nsec = stat->st_ctim.tv_nsec;
 512 }
 513
 514 static void statfs_to_prstatfs(ProxyStatFS *pr_stfs, struct statfs *stfs)
 515 {
 516     memset(pr_stfs, 0, sizeof(*pr_stfs));
 517     pr_stfs->f_type = stfs->f_type;
 518     pr_stfs->f_bsize = stfs->f_bsize;
 519     pr_stfs->f_blocks = stfs->f_blocks;
 520     pr_stfs->f_bfree = stfs->f_bfree;
 521     pr_stfs->f_bavail = stfs->f_bavail;
 522     pr_stfs->f_files = stfs->f_files;
 523     pr_stfs->f_ffree = stfs->f_ffree;
 524     pr_stfs->f_fsid[0] = stfs->f_fsid.__val[0];
 525     pr_stfs->f_fsid[1] = stfs->f_fsid.__val[1];
 526     pr_stfs->f_namelen = stfs->f_namelen;
 527     pr_stfs->f_frsize = stfs->f_frsize;
 528 }
 529
 530 /*
 531  * Gets stat/statfs information and packs in out_iovec structure
 532  * on success returns number of bytes packed in out_iovec struture
 533  * otherwise returns -errno
 534  */
 535 static int do_stat(int type, struct iovec *iovec, struct iovec *out_iovec)
 536 {
 537     int retval;
 538     V9fsString path;
 539     ProxyStat pr_stat;
 540     ProxyStatFS pr_stfs;
 541     struct stat st_buf;
 542     struct statfs stfs_buf;
 543
 544     v9fs_string_init(&path);
 545     retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "s", &path);
 546     if (retval < 0) {
 547         return retval;
 548     }
 549
 550     switch (type) {
 551     case T_LSTAT:
 552         retval = lstat(path.data, &st_buf);
 553         if (retval < 0) {
 554             retval = -errno;
 555         } else {
 556             stat_to_prstat(&pr_stat, &st_buf);
 557             retval = proxy_marshal(out_iovec, PROXY_HDR_SZ,
 558                                    "qqqdddqqqqqqqqqq", pr_stat.st_dev,
 559                                    pr_stat.st_ino, pr_stat.st_nlink,
 560                                    pr_stat.st_mode, pr_stat.st_uid,
 561                                    pr_stat.st_gid, pr_stat.st_rdev,
 562                                    pr_stat.st_size, pr_stat.st_blksize,
 563                                    pr_stat.st_blocks,
 564                                    pr_stat.st_atim_sec, pr_stat.st_atim_nsec,
 565                                    pr_stat.st_mtim_sec, pr_stat.st_mtim_nsec,
 566                                    pr_stat.st_ctim_sec, pr_stat.st_ctim_nsec);
 567         }
 568         break;
 569     case T_STATFS:
 570         retval = statfs(path.data, &stfs_buf);
 571         if (retval < 0) {
 572             retval = -errno;
 573         } else {
 574             statfs_to_prstatfs(&pr_stfs, &stfs_buf);
 575             retval = proxy_marshal(out_iovec, PROXY_HDR_SZ,
 576                                    "qqqqqqqqqqq", pr_stfs.f_type,
 577                                    pr_stfs.f_bsize, pr_stfs.f_blocks,
 578                                    pr_stfs.f_bfree, pr_stfs.f_bavail,
 579                                    pr_stfs.f_files, pr_stfs.f_ffree,
 580                                    pr_stfs.f_fsid[0], pr_stfs.f_fsid[1],
 581                                    pr_stfs.f_namelen, pr_stfs.f_frsize);
 582         }
 583         break;
 584     }
 585     v9fs_string_free(&path);
 586     return retval;
 587 }
 588
 589 static int do_readlink(struct iovec *iovec, struct iovec *out_iovec)
 590 {
 591     char *buffer;
 592     int size, retval;
 593     V9fsString target, path;
 594
 595     v9fs_string_init(&path);
 596     retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "sd", &path, &size);
 597     if (retval < 0) {
 598         v9fs_string_free(&path);
 599         return retval;
 600     }
 601     buffer = g_malloc(size);
 602     v9fs_string_init(&target);
 603     retval = readlink(path.data, buffer, size - 1);
 604     if (retval > 0) {
 605         buffer[retval] = '\0';
 606         v9fs_string_sprintf(&target, "%s", buffer);
 607         retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "s", &target);
 608     } else {
 609         retval = -errno;
 610     }
 611     g_free(buffer);
 612     v9fs_string_free(&target);
 613     v9fs_string_free(&path);
 614     return retval;
 615 }
 616
 617 /*
 618  * create other filesystem objects and send 0 on success
 619  * return -errno on error
 620  */
 621 static int do_create_others(int type, struct iovec *iovec)
 622 {
 623     dev_t rdev;
 624     int retval = 0;
 625     int offset = PROXY_HDR_SZ;
 626     V9fsString oldpath, path;
 627     int mode, uid, gid, cur_uid, cur_gid;
 628
 629     v9fs_string_init(&path);
 630     v9fs_string_init(&oldpath);
 631
 632     retval = proxy_unmarshal(iovec, offset, "dd", &uid, &gid);
 633     if (retval < 0) {
 634         return retval;
 635     }
 636     offset += retval;
 637     retval = setugid(uid, gid, &cur_uid, &cur_gid);
 638     if (retval < 0) {
 639         goto unmarshal_err_out;
 640     }
 641     switch (type) {
 642     case T_MKNOD:
 643         retval = proxy_unmarshal(iovec, offset, "sdq", &path, &mode, &rdev);
 644         if (retval < 0) {
 645             goto err_out;
 646         }
 647         retval = mknod(path.data, mode, rdev);
 648         break;
 649     case T_MKDIR:
 650         retval = proxy_unmarshal(iovec, offset, "sd", &path, &mode);
 651         if (retval < 0) {
 652             goto err_out;
 653         }
 654         retval = mkdir(path.data, mode);
 655         break;
 656     case T_SYMLINK:
 657         retval = proxy_unmarshal(iovec, offset, "ss", &oldpath, &path);
 658         if (retval < 0) {
 659             goto err_out;
 660         }
 661         retval = symlink(oldpath.data, path.data);
 662         break;
 663     }
 664     if (retval < 0) {
 665         retval = -errno;
 666     }
 667
 668 err_out:
 669     resetugid(cur_uid, cur_gid);
 670 unmarshal_err_out:
 671     v9fs_string_free(&path);
 672     v9fs_string_free(&oldpath);
 673     return retval;
 674 }
 675
 676 /*
 677  * create a file and send fd on success
 678  * return -errno on error
 679  */
 680 static int do_create(struct iovec *iovec)
 681 {
 682     int ret;
 683     V9fsString path;
 684     int flags, mode, uid, gid, cur_uid, cur_gid;
 685
 686     v9fs_string_init(&path);
 687     ret = proxy_unmarshal(iovec, PROXY_HDR_SZ, "sdddd",
 688                           &path, &flags, &mode, &uid, &gid);
 689     if (ret < 0) {
 690         goto unmarshal_err_out;
 691     }
 692     ret = setugid(uid, gid, &cur_uid, &cur_gid);
 693     if (ret < 0) {
 694         goto unmarshal_err_out;
 695     }
 696     ret = open(path.data, flags, mode);
 697     if (ret < 0) {
 698         ret = -errno;
 699     }
 700
 701     resetugid(cur_uid, cur_gid);
 702 unmarshal_err_out:
 703     v9fs_string_free(&path);
 704     return ret;
 705 }
 706
 707 /*
 708  * open a file and send fd on success
 709  * return -errno on error
 710  */
 711 static int do_open(struct iovec *iovec)
 712 {
 713     int flags, ret;
 714     V9fsString path;
 715
 716     v9fs_string_init(&path);
 717     ret = proxy_unmarshal(iovec, PROXY_HDR_SZ, "sd", &path, &flags);
 718     if (ret < 0) {
 719         goto err_out;
 720     }
 721     ret = open(path.data, flags);
 722     if (ret < 0) {
 723         ret = -errno;
 724     }
 725 err_out:
 726     v9fs_string_free(&path);
 727     return ret;
 728 }
 729
 730 /* create unix domain socket and return the descriptor */
 731 static int proxy_socket(const char *path, uid_t uid, gid_t gid)
 732 {
 733     int sock, client;
 734     struct sockaddr_un proxy, qemu;
 735     socklen_t size;
 736
 737     /* requested socket already exists, refuse to start */
 738     if (!access(path, F_OK)) {
 739         do_log(LOG_CRIT, "socket already exists\n");
 740         return -1;
 741     }
 742
 743     if (strlen(path) >= sizeof(proxy.sun_path)) {
 744         do_log(LOG_CRIT, "UNIX domain socket path exceeds %zu characters\n",
 745                sizeof(proxy.sun_path));
 746         return -1;
 747     }
 748
 749     sock = socket(AF_UNIX, SOCK_STREAM, 0);
 750     if (sock < 0) {
 751         do_perror("socket");
 752         return -1;
 753     }
 754
 755     /* mask other part of mode bits */
 756     umask(7);
 757
 758     proxy.sun_family = AF_UNIX;
 759     strcpy(proxy.sun_path, path);
 760     if (bind(sock, (struct sockaddr *)&proxy,
 761             sizeof(struct sockaddr_un)) < 0) {
 762         do_perror("bind");
 763         goto error;
 764     }
 765     if (chown(proxy.sun_path, uid, gid) < 0) {
 766         do_perror("chown");
 767         goto error;
 768     }
 769     if (listen(sock, 1) < 0) {
 770         do_perror("listen");
 771         goto error;
 772     }
 773
 774     size = sizeof(qemu);
 775     client = accept(sock, (struct sockaddr *)&qemu, &size);
 776     if (client < 0) {
 777         do_perror("accept");
 778         goto error;
 779     }
 780     close(sock);
 781     return client;
 782
 783 error:
 784     close(sock);
 785     return -1;
 786 }
 787
 788 static void usage(char *prog)
 789 {
 790     fprintf(stderr, "usage: %s\n"
 791             " -p|--path <path> 9p path to export\n"
 792             " {-f|--fd <socket-descriptor>} socket file descriptor to be used\n"
 793             " {-s|--socket <socketname> socket file used for communication\n"
 794             " \t-u|--uid <uid> -g|--gid <gid>} - uid:gid combination to give "
 795             " access to this socket\n"
 796             " \tNote: -s & -f can not be used together\n"
 797             " [-n|--nodaemon] Run as a normal program\n",
 798             basename(prog));
 799 }
 800
 801 static int process_reply(int sock, int type,
 802                          struct iovec *out_iovec, int retval)
 803 {
 804     switch (type) {
 805     case T_OPEN:
 806     case T_CREATE:
 807         if (send_fd(sock, retval) < 0) {
 808             return -1;
 809         }
 810         break;
 811     case T_MKNOD:
 812     case T_MKDIR:
 813     case T_SYMLINK:
 814     case T_LINK:
 815     case T_CHMOD:
 816     case T_CHOWN:
 817     case T_TRUNCATE:
 818     case T_UTIME:
 819     case T_RENAME:
 820     case T_REMOVE:
 821     case T_LSETXATTR:
 822     case T_LREMOVEXATTR:
 823         if (send_status(sock, out_iovec, retval) < 0) {
 824             return -1;
 825         }
 826         break;
 827     case T_LSTAT:
 828     case T_STATFS:
 829     case T_READLINK:
 830     case T_LGETXATTR:
 831     case T_LLISTXATTR:
 832     case T_GETVERSION:
 833         if (send_response(sock, out_iovec, retval) < 0) {
 834             return -1;
 835         }
 836         break;
 837     default:
 838         return -1;
 839         break;
 840     }
 841     return 0;
 842 }
 843
 844 static int process_requests(int sock)
 845 {
 846     int flags;
 847     int size = 0;
 848     int retval = 0;
 849     uint64_t offset;
 850     ProxyHeader header;
 851     int mode, uid, gid;
 852     V9fsString name, value;
 853     struct timespec spec[2];
 854     V9fsString oldpath, path;
 855     struct iovec in_iovec, out_iovec;
 856
 857     in_iovec.iov_base  = g_malloc(PROXY_MAX_IO_SZ + PROXY_HDR_SZ);
 858     in_iovec.iov_len   = PROXY_MAX_IO_SZ + PROXY_HDR_SZ;
 859     out_iovec.iov_base = g_malloc(PROXY_MAX_IO_SZ + PROXY_HDR_SZ);
 860     out_iovec.iov_len  = PROXY_MAX_IO_SZ + PROXY_HDR_SZ;
 861
 862     while (1) {
 863         /*
 864          * initialize the header type, so that we send
 865          * response to proper request type.
 866          */
 867         header.type = 0;
 868         retval = read_request(sock, &in_iovec, &header);
 869         if (retval < 0) {
 870             goto err_out;
 871         }
 872
 873         switch (header.type) {
 874         case T_OPEN:
 875             retval = do_open(&in_iovec);
 876             break;
 877         case T_CREATE:
 878             retval = do_create(&in_iovec);
 879             break;
 880         case T_MKNOD:
 881         case T_MKDIR:
 882         case T_SYMLINK:
 883             retval = do_create_others(header.type, &in_iovec);
 884             break;
 885         case T_LINK:
 886             v9fs_string_init(&path);
 887             v9fs_string_init(&oldpath);
 888             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ,
 889                                      "ss", &oldpath, &path);
 890             if (retval > 0) {
 891                 retval = link(oldpath.data, path.data);
 892                 if (retval < 0) {
 893                     retval = -errno;
 894                 }
 895             }
 896             v9fs_string_free(&oldpath);
 897             v9fs_string_free(&path);
 898             break;
 899         case T_LSTAT:
 900         case T_STATFS:
 901             retval = do_stat(header.type, &in_iovec, &out_iovec);
 902             break;
 903         case T_READLINK:
 904             retval = do_readlink(&in_iovec, &out_iovec);
 905             break;
 906         case T_CHMOD:
 907             v9fs_string_init(&path);
 908             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ,
 909                                      "sd", &path, &mode);
 910             if (retval > 0) {
 911                 retval = chmod(path.data, mode);
 912                 if (retval < 0) {
 913                     retval = -errno;
 914                 }
 915             }
 916             v9fs_string_free(&path);
 917             break;
 918         case T_CHOWN:
 919             v9fs_string_init(&path);
 920             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sdd", &path,
 921                                      &uid, &gid);
 922             if (retval > 0) {
 923                 retval = lchown(path.data, uid, gid);
 924                 if (retval < 0) {
 925                     retval = -errno;
 926                 }
 927             }
 928             v9fs_string_free(&path);
 929             break;
 930         case T_TRUNCATE:
 931             v9fs_string_init(&path);
 932             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sq",
 933                                      &path, &offset);
 934             if (retval > 0) {
 935                 retval = truncate(path.data, offset);
 936                 if (retval < 0) {
 937                     retval = -errno;
 938                 }
 939             }
 940             v9fs_string_free(&path);
 941             break;
 942         case T_UTIME:
 943             v9fs_string_init(&path);
 944             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sqqqq", &path,
 945                                      &spec[0].tv_sec, &spec[0].tv_nsec,
 946                                      &spec[1].tv_sec, &spec[1].tv_nsec);
 947             if (retval > 0) {
 948                 retval = utimensat(AT_FDCWD, path.data, spec,
 949                                    AT_SYMLINK_NOFOLLOW);
 950                 if (retval < 0) {
 951                     retval = -errno;
 952                 }
 953             }
 954             v9fs_string_free(&path);
 955             break;
 956         case T_RENAME:
 957             v9fs_string_init(&path);
 958             v9fs_string_init(&oldpath);
 959             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ,
 960                                      "ss", &oldpath, &path);
 961             if (retval > 0) {
 962                 retval = rename(oldpath.data, path.data);
 963                 if (retval < 0) {
 964                     retval = -errno;
 965                 }
 966             }
 967             v9fs_string_free(&oldpath);
 968             v9fs_string_free(&path);
 969             break;
 970         case T_REMOVE:
 971             v9fs_string_init(&path);
 972             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "s", &path);
 973             if (retval > 0) {
 974                 retval = remove(path.data);
 975                 if (retval < 0) {
 976                     retval = -errno;
 977                 }
 978             }
 979             v9fs_string_free(&path);
 980             break;
 981         case T_LGETXATTR:
 982         case T_LLISTXATTR:
 983             retval = do_getxattr(header.type, &in_iovec, &out_iovec);
 984             break;
 985         case T_LSETXATTR:
 986             v9fs_string_init(&path);
 987             v9fs_string_init(&name);
 988             v9fs_string_init(&value);
 989             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sssdd", &path,
 990                                      &name, &value, &size, &flags);
 991             if (retval > 0) {
 992                 retval = lsetxattr(path.data,
 993                                    name.data, value.data, size, flags);
 994                 if (retval < 0) {
 995                     retval = -errno;
 996                 }
 997             }
 998             v9fs_string_free(&path);
 999             v9fs_string_free(&name);
1000             v9fs_string_free(&value);
1001             break;
1002         case T_LREMOVEXATTR:
1003             v9fs_string_init(&path);
1004             v9fs_string_init(&name);
1005             retval = proxy_unmarshal(&in_iovec,
1006                                      PROXY_HDR_SZ, "ss", &path, &name);
1007             if (retval > 0) {
1008                 retval = lremovexattr(path.data, name.data);
1009                 if (retval < 0) {
1010                     retval = -errno;
1011                 }
1012             }
1013             v9fs_string_free(&path);
1014             v9fs_string_free(&name);
1015             break;
1016         case T_GETVERSION:
1017             retval = do_getversion(&in_iovec, &out_iovec);
1018             break;
1019         default:
1020             goto err_out;
1021             break;
1022         }
1023
1024         if (process_reply(sock, header.type, &out_iovec, retval) < 0) {
1025             goto err_out;
1026         }
1027     }
1028 err_out:
1029     g_free(in_iovec.iov_base);
1030     g_free(out_iovec.iov_base);
1031     return -1;
1032 }
1033
1034 int main(int argc, char **argv)
1035 {
1036     int sock;
1037     uid_t own_u;
1038     gid_t own_g;
1039     char *rpath = NULL;
1040     char *sock_name = NULL;
1041     struct stat stbuf;
1042     int c, option_index;
1043 #ifdef FS_IOC_GETVERSION
1044     int retval;
1045     struct statfs st_fs;
1046 #endif
1047
1048     is_daemon = true;
1049     sock = -1;
1050     own_u = own_g = -1;
1051     while (1) {
1052         option_index = 0;
1053         c = getopt_long(argc, argv, "p:nh?f:s:u:g:", helper_opts,
1054                         &option_index);
1055         if (c == -1) {
1056             break;
1057         }
1058         switch (c) {
1059         case 'p':
1060             rpath = g_strdup(optarg);
1061             break;
1062         case 'n':
1063             is_daemon = false;
1064             break;
1065         case 'f':
1066             sock = atoi(optarg);
1067             break;
1068         case 's':
1069             sock_name = g_strdup(optarg);
1070             break;
1071         case 'u':
1072             own_u = atoi(optarg);
1073             break;
1074         case 'g':
1075             own_g = atoi(optarg);
1076             break;
1077         case '?':
1078         case 'h':
1079         default:
1080             usage(argv[0]);
1081             exit(EXIT_FAILURE);
1082         }
1083     }
1084
1085     /* Parameter validation */
1086     if ((sock_name == NULL && sock == -1) || rpath == NULL) {
1087         fprintf(stderr, "socket, socket descriptor or path not specified\n");
1088         usage(argv[0]);
1089         return -1;
1090     }
1091
1092     if (sock_name && sock != -1) {
1093         fprintf(stderr, "both named socket and socket descriptor specified\n");
1094         usage(argv[0]);
1095         exit(EXIT_FAILURE);
1096     }
1097
1098     if (sock_name && (own_u == -1 || own_g == -1)) {
1099         fprintf(stderr, "owner uid:gid not specified, ");
1100         fprintf(stderr,
1101                 "owner uid:gid specifies who can access the socket file\n");
1102         usage(argv[0]);
1103         exit(EXIT_FAILURE);
1104     }
1105
1106     if (lstat(rpath, &stbuf) < 0) {
1107         fprintf(stderr, "invalid path \"%s\" specified, %s\n",
1108                 rpath, strerror(errno));
1109         exit(EXIT_FAILURE);
1110     }
1111
1112     if (!S_ISDIR(stbuf.st_mode)) {
1113         fprintf(stderr, "specified path \"%s\" is not directory\n", rpath);
1114         exit(EXIT_FAILURE);
1115     }
1116
1117     if (is_daemon) {
1118         if (daemon(0, 0) < 0) {
1119             fprintf(stderr, "daemon call failed\n");
1120             exit(EXIT_FAILURE);
1121         }
1122         openlog(PROGNAME, LOG_PID, LOG_DAEMON);
1123     }
1124
1125     do_log(LOG_INFO, "Started\n");
1126     if (sock_name) {
1127         sock = proxy_socket(sock_name, own_u, own_g);
1128         if (sock < 0) {
1129             goto error;
1130         }
1131     }
1132
1133     if (chroot(rpath) < 0) {
1134         do_perror("chroot");
1135         goto error;
1136     }
1137     if (chdir("/") < 0) {
1138         do_perror("chdir");
1139         goto error;
1140     }
1141
1142     get_version = false;
1143 #ifdef FS_IOC_GETVERSION
1144     /* check whether underlying FS support IOC_GETVERSION */
1145     retval = statfs("/", &st_fs);
1146     if (!retval) {
1147         switch (st_fs.f_type) {
1148         case EXT2_SUPER_MAGIC:
1149         case BTRFS_SUPER_MAGIC:
1150         case REISERFS_SUPER_MAGIC:
1151         case XFS_SUPER_MAGIC:
1152             get_version = true;
1153             break;
1154         }
1155     }
1156 #endif
1157
1158     umask(0);
1159     if (init_capabilities() < 0) {
1160         goto error;
1161     }
1162
1163     process_requests(sock);
1164 error:
1165     g_free(rpath);
1166     g_free(sock_name);
1167     do_log(LOG_INFO, "Done\n");
1168     closelog();
1169     return 0;
1170 }